I still cant trust her one bit, and think she will double/triple cross the Losties.

She wants to get off the island, she has said as much. What does she have to gain by staying with the Losties and praying for some rescue boat (she knows there wont be one as the island doesnt actually exist on maps)

Ben - although he lies alot - has said she can leave the island if she gets someone to concieve and give birth on the island. Even if he doesnt mean that, he knows how to get off the island and surely if Juliette is ever to get off the island, she needs him?